1. Field of the Invention
The present invention relates generally to medical devices and, more particularly, to patient ventilation devices, such as breathing circuits and tracheal tubes.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring many such characteristics of a patient. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
In the course of treating a patient, a tube or other medical device may be used to control the flow of air, food, fluids, or other substances into the patient. For example, medical devices, such as tracheal tubes, may be used to control the flow of one or more substances into or out of a patient. In many instances it is desirable to provide a seal between the outside of the tube or device and the interior of the passage in which the tube or device is inserted. In this way, substances can only flow through the passage via the tube or other medical device, allowing a medical practitioner to maintain control over the type and amount of substances flowing into and out of the patient.
For example, tracheal tubes may be used to control the flow of air or other gases through a patient's trachea. Such tracheal tubes may include endotracheal (ET) tubes or tracheostomy tubes. To seal these types of tracheal tubes, an inflatable cuff may be associated with these tubes. When inflated, the cuff generally expands into the surrounding trachea to seal the tracheal passage around the tube. In certain cases, the cuffs may form an imperfect seal against a patient's tracheal wall. For example, there are certain types of low pressure cuffs that are sized to about one and a half times the average tracheal diameter. While these cuffs provide the advantage of low pressure contact with the tracheal walls, when these low pressure cuffs are inflated, the oversize cuffs fold up on themselves to fit in the patient's trachea. The folds serve as leak paths for microbe-laden secretions, which may allow microbes to travel from the patient's mouth into the lungs. Other types of cuffs are manufactured from materials that have a lower tendency to form leak paths. For example, high pressure cuffs are typically made of highly elastic materials that may form a relatively smooth seal against the trachea. However, such cuffs have associated disadvantages. Due to their elastic properties, high pressure cuffs are often inflated to at least twice the intracuff pressure of lower pressure cuffs in order to form a sufficient tracheal seal. Such high pressures may cause patient discomfort. Further, the mechanical pressure of the high pressure cuff against the tracheal walls may also cause temporary damage to cilial structures in the trachea that are associated with airway particle clearance.